Hypertonic saline (HS) resuscitation is a promising new approach in the prevention of tissue damage in trauma patients, because of its capacity to block neutrophil (PMN) activation. We havestudied the molecular mechanisms through which HS controls PMNfunction and havefound that HStriggers the release ofATP. ATP can augment PMNresponses via P2 receptors. ATP convertedto adenosine inhibits PMNactivation via P1 receptors. We hypothesize that the balance between ATP and adenosine determines whether HS increases or dampens PMNfunction. Inthe following three Specific Aims, we proposeto define the components that control this ATP/adenosine balance and determine pharmaceutical approaches to shift it toward adenosine, and thus towardinhibition of PMNfunction. Specific Aim 1:ATPrelease and P2receptor activation: Themechanisms of ATP release will bestudied, a novel method for real-time monitoring of ATP release will be established, and P2 receptorsubtype expression and colocalization with sites of ATP release and hydrolysis will be assessed. Specific Aim 2)Adenosine formation and P1receptor activation:Thedynamics of expressionand colocalization of ecto-enzymesgenerating and hydrolyzing adenosine, specifically alkaline phosphatase, adenosine deaminase, and of the P1 receptors that are activated by adenosine will be studied. Specific Aim 3) Modulation of the effect ofHS:Theeffect of ATP released from other cells surrounding PMNwill be studied and pharmacological approachesto improvethe efficacy of HS resuscitation by modulating adenosine accumulation will be tested with humanwhole blood and a mousemodel of hemorrhagic shock. The proposed experiments will elucidate general principles of HS-induced ATP release and the control of PMNfunction by extracellular ATP and its products. This knowledge will allow us to better understand how HS resuscitation can regulate PMNfunction and howthe clinical effectivenessof HScan be optimized to attenuate inflammation and PMN-induced organ damage in trauma victims. PERFORMANCE STTE(S) (organization, city, state) University of California San Diego, UCSD Medical Center, San Diego, California PHS398(Rev. 09/04) Page 2 Form Page 2 Principal Investigator/Program Director(Last, First, Middle): Jlinger, Wolfgang, G. KEY PERSONNEL. Seeinstructions. Usecontinuationpages asneeded to provide the required information in the formatshownbelow. Start with Principal Investigator. List all other key personnelin alphabetical order, last name first. Name eRA CommonsUser Name Organization Role onProject Junger, Wolfgang G. 33jungerw UCSD PI Hoyt, David B. UCSD Co-Investigator Insel, Paul A. UCSD Co-Investigator OTHER SIGNIFICANT CONTRIBUTORS Name Organization Role on Project Human Embryonic Stem Cells 03 No Q Yes If the proposed project involves humanembryonic stem cells, list below the registration number of the specific cell line(s) from the following list http://Stemcells.nih.gov/registrv/index.asp. Usecontinuation pages as needed. If a specific line cannot be referenced at this time, include a statement that one from the Registry will be used. Cell Line Disclosure Permission Statement ApplicabletoSBIR/STTR Only. SeeSBIR/STTR instructions. Q Yes Q NO PHS 398(Rev.09/04) Page 3 Form Page 2-continued Number the followingpages consecutively throughout the application. Do not use suffixes such as 4a, 4b. Principal Investigator/Program Director (Last, First, Middle): Junger, Wolfgang, G. The nameof the principal investigator/program director must be provided atthe top of each printed page and each continuation page. RESEARCH GRANT TABLE OF CONTENTS PageNumbers Face Page 1 Description,